Method of changing surface characteristics of sized glass fibers and fibers having changeable surface characteristics

ABSTRACT

GLASS FIBERES HAVING A COATING THEREON OF A POWDERY TYPE GLASS LUBRICANT HAVING EMULSIFIED PARTICLES OF A THERMOPLASTIC RESIN ADJACENT THE SURFACE OF THE COATING. THE EMULSIFIED PARTICLES ARE SEPARATED BY THE POWDERY TYPE LUBRICANT TO PROVIDE A SURFACE ADAPTABLE FOR INITIAL STAGES OF FABRICATION, FOLLOWING WHICH THE COATED FIBERS ARE HEAT TREATED TO AGGLOMERATE THE HEAT SOFTENABLE PARTICLES AND CHANGE THE SURFACE CHARACTERISTICS OF THE COATED FIBERS FOR SUBSEQUENT PROCESSING AND/OR USE. IN A PROFERRED EMBODIMENT, THE HEAT SOFTENABLE PARTICLES ARE CAUSED TO CONGREGATE AT THE SURFACE OF THE COATING BY REASON OF AN ANIONIC EMULSIFYING AGENT. IN THE MOST PERFERRED EMBODIMENT. THE COATING IS PRIMARILY A STARCH COATING WITH THE EMULSIFIED PARTICLES OF THE HEAT SOFTENABLE RESIN KEPT SEPARATED BY THE STARCH. AFTER THE TWISTING OPERATION, THE COATED FIBERS ARE, THOROUGHLY DRIED AND HEATED ABOVE THE SOFTENABLE POINT OF THE RESIN TO PROVIDE A CONTROLLED ADHESION BETWEEN THE FIBERS.

Aug. 13, 1974 H. 1.. HAYNES EIAL 3,829,302

METHOD OF CHANGING SURFACE CHARACTERISTICS OF SIZED GLASS FIBERS AND FIBERS HAVING CHANGEABLE SURFACE CHARACTERISTICS v Filed April 10, 1972 United States Patent METHOD OF CHANGING SURFACE CHARACTER- ISTICS OF SIZED GLASS FIBERS AND FIBERS HAVING CHANGEABLE SURFACE CHARAC- TERISTICS Harold L. Haynes, Granville, and Michael J. Harvey, Newark, Ohio, assignors to Owens-Coming Fiberglas Corporation Filed Apr. 10, 1972, Ser. No. 242,628 Int. Cl. G03c 25/02 US. Cl. 65-3 Claims ABSTRACT OF THE DISCLOSURE Glass fibers having a coating thereon of a powdery type glass lubricant having emulsified particles of a thermoplastic resin adjacent the surface of the coating. The emulsified particles are separated by the powdery type lubricant to provide a surface adaptable for initial stages of fabrication, following which the coated fibers are heat treated to agglomerate the heat softenable particles and change the surface characteristics of the coated fibers for subsequent processing and/or use. In a preferred embodiment, the heat softenable particles are caused to congregate at the surface of the coating by reason of an anionic emulsifying agent. In the most preferred embodiment, the coating is primarily a starch coating with the emulsified particles of the heat softenable resin kept separated by the starch. After the twisting operation, the coated fibers are, thoroughly dried and heated above the softenable point of the resin to provide a controlled adhesion between the fibers.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic elevational view of apparatus for forming coiled packages of continuous glass fibers;

FIG. 2 is a schematic elevational view of apparatus for unwinding the glass fiber strand from the coiled package, and twisting and winding the twisted strand onto a twist bobbin;

FIG. 3 is a schematic plan view of apparatus used for pulling the strand from the twist bobbin at high rates of speed as required by subsequent processing machinery that is abruptly stopped and started; and

FIG. 4 is a schematic sectional view of abutting coils of the coated strand as adhered together on the twist bobbin.

BACKGROUND OF THE INVENTION Glass fibers have long been produced by the process shown in FIG. 1 wherein molten streams of glass 10 are pulled from small openings in the bottom 12 of a glass furnace. The streams solidify and are pulled over a moving belt type applicator 14 the surface of which is continuously supplied with an aqueous starch dispersion. The fibers pass over the belt of the applicator 14 while in a separated condition and thereafter are pulled to the side over a graphite shoe 16 which pulls the individual fibers into a strand wherein the fibers are in touching engagement. The strand proceeds past a traverse mechanism 18 onto the surface of a revolving cardboard tube 20 that is mounted on a rotating mandrel 22 which winds the strand into a coiled package 24. The coiled package 24 is removed from the mandrel and dried over night at room temperature to leave a starch coating which contains approximately 25% moisture. The sizes which have been applied by the applicator 14 have conventionally been an aqueous dispersion of starch containing cationic and nonionic oils which protect the fibers from abrasion during the necessary processing operations such as twisting, quilling, beaming, and weaving. The water and cationic lubri- 3,829,302 Patented Aug. 13, 1974 ice cant plays an important part in protecting the fibers during the movement over the belt 14, gathering shoe 16, and the violent rubbing action of the traverse mechanism 18.

The twisting operation shown in FIG. 2 cannot be done wet and in order to protect the fibers during the twisting operation there must be a dry powdery lubricant present, which lubricant has conventionally been starch. As shown in FIG. 2, the strand from the coiled package 24 is drawn downwardly over a control bar 26 which in turn operates a switch mechanism 28 for stopping the twisting operation should the strand break. The action of the strand over the bar 26 holds the switch in an actuated position and the strand thereafter passes through a guide eye 30 that is positioned axially over the top of a twist bobbin 32.

The twist bobbin 32 is mounted on a spindle 34 that is in turn rotated by a pulley 36 over which a continuous drive belt passes. The twist bobbin 32 is surrounded by a small annular rail 38 having radially outwardly extending top and bottom lips 40. A C-shaped plastic clip 42 is snapped over the rail in a position where it is retained by the lips 40, and the strand passes through the guide eye 30, passes underneath the C-shaped clip 42, and proceeds radially to the rotating bobbin. The rotating bobbin pulls the strand with a slight tangential component which causes the C- shaped clip to slide around the rail at a relatively slow rate of speed to help provide uniformity of the wind onto the twist bobbin 44. The rail 38 is moved axially upwardly and downwardly with a programmed movement which always terminates opposite the bottom of the bobbin but which gradually decreases in its upward movement as the winding operation proceeds to build a twist package the upper end of which is tapered.

Prior to the present invention, the twist bobbins have been stored at room temperature awaiting use for winding quill bobbins, forming beams, and other uses. In all of these operations, the twist bobbins 44 are held stationary (usually on a creel) and the strand is pulled endwise off of the twist bobbin 44 through a guide eye 46 that is positioned endwise from the twist bobbin. The strand proceeds through the guide eye 46 and around three tensioning devices T each of which consist of a center post 48 projecting vertically from a smooth friction surface 50. A thin annular weight 52 is position around the post 48 over the strand to provide a small clamping action on the strand. The tensioning devices T are positioned in offset fashion so that the strand changes direction by degrees while passing through the first tension device and degrees while passing through the second and third tensioning devices T. Thereafter the strand passes through another guide eye 54 and then through one of a plurality of openings in an alignment plate 56 that is adapted to group a number of strands being pulled from a number of twist bobbins by subsequent processing machinery.

In order for the strand to be pulled from a stationary bobbin, it is necessary that the end of the package from which the strand is removed be tapered in order that the strand can slide free. In those instances Where the subsequent machinery is slowly started and stopped, the inertia of the strand as it uncoils from the twist bobbin presents no appreciable problem, and the same dry powdery surface of the strand required for the twisting operation is adequate for the subsequent operations. In those instances where the coil is uncoiled from the twist bobbin and fed from the alignment plate 56 directly to high speed operations which are stopped and started abruptly, the uncoiling of the strand causes a whipping action around the stationary bobbin which throws the strand radially outwardly from the bobbin. When stopped abruptly, this whipping action produces snarls at the entrance to the guide eye 46 and upon subsequent start up, a knot is produced and the strand is broken.

An object of the present invention is the provision of a new and improved mechanism, be it mechanical or chemical, which will permit the strand to be uncoiled from the stationary twist bobbin by high speed machinery that is stopped and started abruptly without producing snarls.

Another object of the invention is the provision of a new and improved method of changing the surface characteristics of a glass fiber size coating which will permit the coating to be of a dry lubricious nature during an initial stage and later be changed to a surface of a more resinous nature.

A more specific object of the present invention is the provision of a new and improved starch base coating on glass fibers which can be heat treated after the twisting operation to provide a controlled adhesion between the coils on the twist bobbin which will prevent the coils from being unraveled when pulling action on the strand is stopped abruptly.

Further objects and advantages of the invention will become apparent to those skilled in the art from the following description of the preferred embodiments described with reference to the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the invention, a mechanism is provided whereby spaced apart emulsified particles of a thermoplastic resin are caused to arrange themselves adjacent the surface of a dry powdery film on glass fibers to provide an ititial coating whose surface exhibits properties that are substantially those of the dry powdery film forming material. After protecting the fibers during operations which require the dry powdery nature, the coated fibers are heated above the softening point of the resin to change the surface characteristics of the coating.

In the preferred application of the above principles, glass fibers are coated with an aqueous dispersion of a starch containing size that contains emulsified particles of a thermoplastic resin that are coated with an anionic emulsifying agent. The material is applied to glass fibers at forming, and the water and starch protects the fibers from being abraded by the rubbing action of the traverse and winding machinery. Because the emulsified particles of the thermoplastic resin are anionically charged, they space themselves apart from each other, and from the negatively charged glass to accumulate at the surface of the coating on the fibers with the starch dispersion between and over the emulsified particles. Upon drying the surface of the coating exhibits the properties of starch, and even though a thermoplastic resin is present, the coated strand performs during twisting, etc. with substantially the same characteristics as do prior art starch size coatings. After the fibers are twisted and wound onto the twist bobbin, the twist bobbin is heated to remove substantially all interferring water from around the emulsified particles, and cause the thermoplastic particles to flow through discontinuities in the starch coatings to the surface of the coating.

In the preferred embodiment, the heating operation is carried out to cause some of the thermoplastic particles on each coil of a twist bobbin to fiow into contact with particles of an adjacent coil. Upon cooling, the particles of adjacent coils fuse together to give a controlled bond between the coils. The fused particles are surrounded by starch, and when the fbers are uncoiled from the twist bobbin, the fused particles are pulled out of the starch coating of one of the coils. The force required to pull the fused particles out of the starch coating is small enough that it can be done without breaking the strand, but large enough to prevent the coils from being pulled apart by the inertia of the strand during the uncoiling operation.

The softening points of thermoplastic resins are generally within approximately 5 C. of the glass transition temperature commonly designated Tg, and thermoplastic resins having various softening points can be used so long as the heat treatment is of a sufficient temperature and duration to flow the thermoplastic resin to the extent required for the desired surface modification. In size systems for glass fibers, the upper limit of the Tg will generally be approximately 50C. in order that the heat treatment required to produce the necessary resin flow will not be so high as to destroy the starch coating. Thermoplastic resins having a Tg below approximately 20 C. are the most desirable, while those having a Tg below 0 C. and are nonfiowing at room temperature, are the most preferred materials.

EXAMPLE 1 An aqueous size formulation is made from the following materials and approximate percentages by weight:

Materials: Percent by weight Starch containing 9% by weight of benzyl ether groups 2.500 Pearl starch 1.500 Spermafol wax 1.000 Paraffin wax (melting point 123 F.) 0.250 1 Emulsifier (polyoxyethylenesorbitan monostearate) (sorbitan monostearate) 0.120

Cationic lubricant (reaction product of tetraethylene and stearic acid in a molar ratio of 1 to 2.0) 0.175 Nonionic emulsifier nonyl phenoxy poly (ethyleneoxy) ethanol Emulsified particles of ethylacrylate methylmethacrylate copolymer having a Tg of l1 C. and emulsified with sodium napthalene sulfanate (solids) 1.000 Water Balance The size formulation is prepared by sifting the benzylated starch into approximately /2 of the necessary water and allowing it to disperse. Thereafter the pearl starch is added and dispersed and the starch slurry is heated to 185 F. for 30 minutes. Thereafter some of the balance of the water is added to quench the degree of cook to leave 10% swollen but unburst granules. The waxes, sorbitan monostearate and polyoxyethylene sorbitan monostearate are mixed together and melted at F. The molten material is mixed by a motor driven agitator and water at F. is slowly added until the emulsion thickens. Thereafter the speed of agitation is increased and water at 180 F. is slowly added until the emulsion inverts. The cationic lubricant is diluted with water at 180 F. and added, and the wax emulsion is violently mixed until homogenized. The wax and cationic lubricant mixture is cooled to 150 F. and the mixture is added to the cooked starch. Thereafter the nonyl phenoxy poly (ethyleneoxy) ethanol is added to stabilize the emulsion and an emulsion containing anionically emulsified ethylacrylate at 50% solids is blended therein. The mixture is cooled to 140 F. and is applied to the glass fibers at forming by the process shown in FIG. 1.

The coiled package of fibers so produced was dried over night at room temperature to give a coating of 1.0% by weight of solids based on the solids weight of coated fibers, and which contained an additional /2% of moisture based on the solids weight of coated fibers. The coating, therefore, comprised approximately 20% water. The package was then used to produce bobbins of twisted strands according to the procedures indicated in FIG. 2 of the drawings. The twisting operation proceeded in as good a manner as occurs when the emulsified particles of ethylacrylate are not included in the sizing materials. The twist bobbins so produced were then heated in a drying oven at 180 -F. for 16 hours during which time the surface characteristics of the strands were changed by a controlled exudation of the ethylacrylate to the surface. The twist bobbins were then cooled to room temperature so that touching particles of ethylacrylate of adjacent coils fused together. The strands from the twist bobbins were then fed to paper-making machinery through the apparatus depicted in FIG. 3. The paper-making machinery operated at approximately 10,000 feet per minute and was stopped and started abruptly without producing snarls and knots and without breaking of the strand.

By way of contrast, glass fibers similarly processed excepting that the emulsified particles of ethylacrylate were not used, could not be pulled from the twist bobbins by papermaking machinery which was abruptly stopped and started without breaking. When the paper-making machinery was stopped, inertia of the fibers produced a snarl at the end of the bobbin. A high percentage of these snarls developed into knots which broke the strand.

EXAMPLE 2 EXAMPLE 3 The process of Example 1 is repeated excepting that the emulsified particles of the ethylacrylate copolymer are replaced with an emulsion of polyvinylacetate that is emulsified with sodium tridecyl sulfate. This material has generally the same properties as does the material of Example 1.

EXAMPLE 4 The process of Example 3 is repeated excepting that the polyvinylacetate is emulsified with a nonionic emulsifying agent. This material also breaks excessively during stopping and starting of the paper-making machinery.

EXAMPLE 5 The process of Example 1 is repeated excepting that the emulsified particles of the ethylacrylate copolymer are replaced by emulsified particles of a polyurethane that is auionically emulsified by sodium tridecyl sulfate. This material processes through the paper-making machinery satisfactorily without breaking as does the material of Example 1.

EXAMPLE 6 The process of Example 1 is repeated excepting that the ethylacrylate copolymer is replaced with emulsified particles of ethylacrylate having a Tg of minus 20 C. This material has generally the same properties as does the material of Example 1.

In general, sizes for glass fibers can be made from the following materials in the approximate percentages by weight given below:

Ingredients: Percent by weight Starch /26 Emulsified nonionic lubricant particles 0 2 Cationic lubricant 0-2 Particles of a thermoplastic resin having a Tg less than 50 C 0.50-2 Water Balance The starch is preferably cooked so that swollen but unburst granules remain and also preferably includes a portion of granules which have been etheri-fied or esterified with hydrocarbons and substituted hydrocarbons to increase compatibility with the wax. The hydrocarbons and substituted hydrocarbons preferably contain phenyl groups and substituted phenyl groups. The cationic lubricant is desirable and is preferably included in an amount between approximately 0.1% and 2.0% to reduce abrasion while the fibers are wet. The nonionic lubricant particles are preferably used in an amount of more than approximately and are preferably a solid such as wax, but nonionic oils can be used. The nonionic lubricant particles help to space the emulsified particles of thermoplastic resin apart to control agglomeration during the heat-treating step. Underivatized starch, such as pearl starch, can be used as a diluent for approximately twothirds of the total starch to give starch film forming properties. Any cationic oil which is soluble in water can be used as the cationic lubricant. Any thermoplastic resin can be used, so long as it has an appropriate Tg for the heat-treatment of the coated strand. Obviously the heattreating temperature can be reduced as the Tg of the resin used is reduced.

EXAMPLE 7 The process of Example 1 is repeated excepting that the ethylacrylate methylmethacrylate copolymer is replaced by a 50% ethylene-50% vinyl chloride copolymer in emulsified form, and which is emulsified with an anionic emulsifying agent. The glass fibers so produced had generally the same properties as did the fibers produced by the process of Example 1.

EXAMPLE 8 The process of Example 1 is repeated excepting that the emulsified particles of ethylacrylate methylmethacrylate copolymer were replaced by 0.2% by weight of solids of a dispersion of. a material having the following formula:

wherein: R is CH3 @MD- IHa and R is the hydrocarbon group of oleic acid, and X provides a polyoxyethylene stearate group of a molecular weight of approximately 400. For a preparation of the above material, see Example 7 of US. Pat. 3,336,253. The coated fibers, so produced have some of the improved properties of the fibers of Example 1. This material while it is cationic when dispersed in water, loses its cationic nature when dried, and runs to the surface of the starch coating where it contacts similar material on another coil of the strand to adhere the coils together. This example demonstrates that the heat treatment of the invention will cause resin particles that are not held to the glass to run to the surface of a starch base coating and agglomerate. Anionic particles are initially deposited adjacent the surface of a starch coating on glass fibers and is the most preferred arrangement for this reason.

A preferred group of sizes will have the following compositions:

Ingredients: .Percentby weight Benzylated starch ether /2-3 Pearl starch /2-3 Wax 4-2 Cationic lubricant 0.1-2 Anionically emulsified thermoplastic particles 0.50-2

Water Balance 7 of those skilled in the art to which the invention relates.

We claim:

1. In the process of producing glass fibers wherein molten streams of glass are attenuated, are coated with a protective glass sizing material dispersed in water, and are gathered into a strand which is wound into a coiled package, the improvement comprising: encorporating emulsified particles of a thermoplastic material having a Tg less than 50. C. into the sizing material, said particles having a coating of an anionic surface active agent thereon, and heating the strand above the Tg temperature of the resin to agglomerate particles of the resin and change the surface characteristics of the coating of the fibers sufiiciently to adhere the coils of the package together at closely spaced points to a degree which avoids tangling of the coils when endwise removal of the coils from the package is abruptly stopped.

2. The process of claim 1 wherein said coating material includes gelatinized starch.

3. The process of claim 1 wherein said coating material includes emulsified particles of wax having a coating thereon of a nonionic surface active agent.

4. The process of manufacturing glass fibers comprising: coating glass fibers with an aqueous dispersion of a powdery type sizing material for sizing glass and emulsified particles of a thermoplastic resin having a Tg below approximately 50 C., coiling the fibers into a package, drying the package at approximately room temperature, removing the fibers from the package to twist the fibers and form a coiled package of the twisted strand, and heating the coiled package of twisted strand above the Tg temperature of the resin to agglomerate particles of the resin and change the surface characteristics of the coating on the fibers sufiiciently to adhere the coils of the package together at closely spaced points to a degree which avoids tangling of the coils when endwise removal of the coils from the package is abruptly stopped.

5. The method of claim 4 wherein the coiled package of twisted strand is heated above the Tg of the resin to modify the bond between coils of the package.

6. The method of claim 4 wherein said polymer is an acrylate the precursor of which is predominantly ethylacrylate.

7. The method of claim 4 wherein the surface of said coating also includes emulsified particles of a Wax.

8. The process of manufacturing glass fibers comprising: coating glass fibers with an aqueous dispersion comprising starch, emulsified particles of wax coated with a nonionic surface active agent, and emulsified particles of a thermoplastic polymer having a Tg below 20 C.; coiling the fibers into a package; drying the package at approximately room temperature; removing the fibers from the package to twist the fibers and form a coiled package of the twisted strand; and heating the coiled package of twisted strand above the boiling point of water to dehydrate the surface of the coating and agglomerate particles of resin to modify the adherence between coils of the twisted strand package sufiiciently to adhere the coils of the package together at closely spaced points to a degree which avoids tangling of the coils when endwise removal of the coils from the package is abruptly stopped.

9. The process of claim 8 wherein the thermoplastic resin is an acrylate having a Tg below minus 0.

10. The process of claim 9 wherein the package of twisted strand is heated at 180 F. for more than four hours.

References Cited UNITED STATES PATENTS 3,284,179 11/1966 Eilerman -3 3,453,652 7/1969 Marzocchi 117-126 GB X 3,615,311 10/1971 Ignatius 65-3 3,664,855 5/1972 Morrison et al. 65-3 X 3,673,027 6/ 1972 Spencer.

ROBERT L. LINDSAY, 111., Primary Examiner US. Cl. X.R. 117-126 GB 

